Dicarboxylic acids may be prepared by processes of various kinds. High yields of carboxylic acids may for example be obtained from renewable sources with a low environmental impact through processes of the oxidative cleavage of unsaturated fatty acids and their derivatives originating from animal and plant oils and fats. Through these processes mixtures of monocarboxylic acids and dicarboxylic acids or their derivatives, which nevertheless require multiple and complex operations for their separation and purification, are obtained.
In particular, when triglycerides containing unsaturated fatty acids, such as for example those present in vegetable oils, are subjected to oxidative cleavage processes, mixtures of monocarboxylic acids and triglycerides containing saturated carboxylic acids with more than one acid functional group are obtained. Patent application WO 2008/138892 describes for example a process in which a fraction of monocarboxylic acids is separated from the oxidative cleavage product of vegetable oils through one or more evaporation and/or distillation operations, depending upon the level of purity required. In patent application WO 2011/080296 the remaining mixture containing triglycerides with more than one acid functional group subsequently undergoes hydrolysis to release further carboxylic acids from the triglycerides containing them. The product obtained nevertheless still contains a mixture of monocarboxylic and dicarboxylic acids and therefore requires further purification steps to obtain dicarboxylic acids which can be used in applications requiring a high degree of purity, such as for example use as monomers in polymerisation reactions.